At least two metabolic defects contribute to the development of type 2 diabetes mellitus: relative insulin insufficiency and insulin resistance. The majority of patients with type 2 diabetes mellitus demonstrate some degree of insulin resistance. Even in the absence of hyperglycemia (high blood sugar), insulin resistance is associated with a cluster of metabolic abnormalities that increase the risk for cardiovascular disease, including dyslipidemia (unhealthy blood fat), increased expression of inflammatory markers, activation of pro-coagulants (pro-clotting), hemodynamic changes, and endothelial dysfunction.
The dyslipidemia associated with insulin resistance and type 2 diabetes mellitus is characterized by elevated triglyceride levels and decreased high-density lipoprotein (good) cholesterol levels. Although low-density lipoprotein (bad) cholesterol levels may not be significantly elevated in patients with type 2 diabetes mellitus, an increase in the proportion of small, dense low-density lipoprotein cholesterol particles of increased atherogenicity (increased formation of lipid deposits in the arteries) is observed. When compared with individuals without type 2 diabetes mellitus, the risk of cardiovascular disease is 2- to 4-fold greater in patients with type 2 diabetes mellitus, and the dyslipidemia of diabetes is an important contributor to the increased risk in this population.
By targeting the insulin resistance underlying type 2 diabetes mellitus, the thiazolidinedione class of oral antihyperglycemic medications possesses both a glucose-lowering effect and the potential to alter lipid/lipoprotein metabolism. Two thiazolidinediones are currently available for the treatment of type 2 diabetes mellitus: pioglitazone hydrochloride (ACTOS, Takeda Pharmaceuticals North America, Inc, Lincolnshire, IL) and rosiglitazone maleate (Avandia, GlaxoSmithKline, Research Triangle Park, NC).
The purpose of this study is to evaluate the triglyceride-lowering effects of pioglitazone to rosiglitazone in patients with type 2 diabetes mellitus and dyslipidemia who are not receiving any other glucose- or lipid-lowering therapies at the same time as the study medications.
Individuals who participate in this study will provide written informed consent and will be required to commit to a screening visit and approximately 7 additional visits at the study center. Study participation is anticipated to be about 39 weeks (or approximately 8 months). Multiple procedures will occur at each visit which may include fasting, blood collection, physical examinations and electrocardiograms. Participants will be required to follow a diabetic diet, self-monitor their blood glucose and maintain a study diary for the duration of the study.
